Colorado authorities have determined that the gun used to kill the state prisons chief Tom Clements last week was the same weapon used by Evan Ebel in a deadly Texas shootout, but they are trying to determine whether the gunman acted alone or had accomplices.

Police in El Paso County, Colo., said today that ballistics tests confirmed that the gun used by Ebel in a shootout with Texas cops Thursday was the gun that killed Clements at his home two days earlier.

"The confirmation goes well beyond acknowledging the same caliber and brand of ammunition being used, but rather is based on unique, and often microscopic markings left on the casings at both scenes," the El Paso County Sheriff's Office said in a statement.

Ebel is considered a suspect in Clements' murder, according to Lt. Jeff Kramer of the sheriff's department, but police are searching for evidence to indicate whether Clements' assassin had help.

"Investigators are actively pursuing all pieces of information and angles to determine whether Ebel acted alone in the shooting of Tom Clements or if others were involved," the statement read.

"Until we know if others are involved we cannot speak to what his role was," Kramer told ABC News today.

Clements was gunned down at his home Tuesday night, March 19. He was 58.

Ebel was pulled over in Texas two days later in Wise County, Texas, where he shot at a sheriff's deputy and then launched into a high-speed chase and shootout with cops. He was killed by police gunfire.

Investigators immediately suspected a connection between the two incidents, noting that Ebel, a Wheat Ridge, Colo., resident, had recently been paroled from a Colorado prison and that he was driving a black Cadillac with Colorado license plates. The car matched the description of a vehicle seen near Clements' house at the time of the murder.

As an inmate, Ebel was a member of the white supremacist jail gang 211 Crew, and Texas authorities said they were investigating whether he was in Texas on gang-related business.

Colorado police would not comment on any possible motive Ebel might have had for killing Clements.

"We are sensitive to the high profile position in which Mr. Clements served and the fact there could be people who would target him based on his position," the sheriff's department said in a statement. "However, we remain open minded to all investigative possibilities and continue to work all available clues and sources of information."

Police in Denver, Colo., are also investigating whether Ebel was involved in the murder of a pizza delivery man on Sunday, March 17.